Controlled electric pump drive for hydraulic lifting arrangement with gas spring in motor
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Oct 9, 1990
Grant Date -
N/A
app pub date -
Oct 21, 1988
filing date -
Oct 28, 1987
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A hydraulic lifting arrangement for a lift assembly on a materials-handling vehicle includes a working piston-cylinder device (17) for raising and lowering the lift assembly, a reversible pump assembly (40) for operating the piston-cylinder device, and an electric motor for driving the pump assembly. The piston-cylinder device (17) is a double-acting device and has two working chambers (28,29), which are connected to the pump assembly by connecting pipes (46,47). The pump assembly comprises a first and a second hydraulic pump (41,42) having fixed displacements. The pumps are so arranged in the system that together they supply hydraulic medium to and receive hydraulic medium from solely the first chamber (28) whereas only the pump motor (41) supplies and receives hydraulic medium to and from the second chamber (29). The relationship between the displacement of the first pump (41) and the sum of the displacements of both pumps (41,42) corresponds essentially to the relationship between the respective active piston areas in the second and the first chambers. Conveniently, a pressure-gas chamber (26) is arranged in the piston-cylinder device for biassing the piston (19) so as to enable the dead weight of the lift assembly and a given part of the load to be counter-balanced.
First Claim
Family
International Classification(s)
Cited Art Landscape
Patent Citation Ranking
Recipient Email Address
Recipient Email Address
Comment
Recipient Email Address
Add to Portfolio(s)
To add this patent to one, or more, of your portfolios, simply click the add button.
This Patent is in these Portfolios:
Add to additional portfolios:
Last Refreshed On:
Changes done successfully